The present invention relates to a dunnage conversion machine with translating grippers, and a method of converting sheet material into a dunnage product using the translating grippers, and a dunnage product.
Various types of conversion machines heretofore have been used to convert sheet stock material composed of one or more plies of sheet material into a dunnage product. Some machines function solely to produce a void fill dunnage product, used primarily to fill voids in a packaging container to prevent the contents thereof from shifting during shipment. One objective in the design of these machines is to produce the void fill dunnage product very rapidly. Accordingly, these machines are designed to operate at relatively high speeds.
Other machines function to produce a dunnage product having cushioning characteristics which enable the dunnage product to, for example, cushion or secure an article in a container from damage which may not otherwise be obtainable from a void fill dunnage product. Such machines usually produce the dunnage product at a relatively slower rate than void fill producing conversion machines to enable deforming or shaping of the sheet material to, for example, impart adequate loft into the resulting dunnage product. Thus, with these machines often speed is sacrificed to achieve a dunnage product characterized by substantial cushioning properties. The trade off is a slower production rate of the cushioning dunnage product as compared to the void fill dunnage product.
However, attempts to achieve a dunnage conversion machine capable of producing a void fill product at relatively higher speeds while still maintaining an adequate void fill and/or cushioning capability have not been without problems. Thus, some conversion machines may fail to impart sufficient loft, or an adequate low density, to the sheet material to be converted, resulting in a dunnage product having an undesirably flat, essentially two dimensional, configuration rather than a more desirable three dimensional void fill configuration. In this instance, manual labor is often used to further convert, e.g., crumple, the dunnage product so that it has more desirable void fill capability. Also, the inventors of the present invention have observed that in some dunnage conversion machines the feeding device may engage the sheet stock material at a concentrated portion thereof and/or too abruptly causing sudden increases in the tension of the sheet material which may tear and/or jam the machine, or otherwise deleteriously affect the cushioning characteristics of the dunnage product, or its ability to adequately protect against damage or breakage of the item to be protected.
Thus, it would be desirable to provide a more effective and efficient conversion machine and method suitable for producing a void fill material having adequate void fill capabilities as well as cushioning characteristics (if desired), for example, one which is lightweight with a low density, yet stable, making it suitable for filling the void space around an article to be packaged and for at least minimally protectively cushioning the article from damage during storage or shipment. More particularly, it would be desirable to provide improved speeds at which the dunnage conversion machine operates and consequently its corresponding output rate, while keeping with the objective of providing a void fill product having at least minimal cushioning characteristics.
The present invention provides a dunnage conversion machine which is particularly suited to production of a void fill dunnage product. According to one general aspect of the invention, opposing grippers including apertures move through a transfer region and laterally capture a crumpled strip of dunnage for advancing the strip of dunnage through the conversion machine. According to another general aspect of the invention, a severing member (such as a blade) is connected to a reciprocating actuator by a motion transmitting assembly that moves the severing member through a full severing cycle upon a single stroke of the actuator in either direction. According to a further general aspect of the invention, a void fill dunnage product includes a three dimensional crumpled strip of dunnage of generally cylindrical shape including at least one ply of sheet material forming multiple substantially longitudinally extending crumpled lobes dispersed in an irregular pattern in cross-section.
The void fill product preferably has the highest possible volume and stability, while using the least possible amount of raw material. This is achieved in accordance with the present invention by producing the noted generally cylindrical product whose stability can yet be further increased by making the same generally curved and/or by permanently deforming the cross-sections of selected spaced portions of the product.
More particularly and according to an aspect of the invention, there is provided a dunnage conversion machine and a method for converting sheet material into a dunnage product, the machine including a forming assembly for shaping the sheet material into a continuous strip of dunnage having a three-dimensional shape, and a pulling assembly positioned downstream from the forming assembly for advancing the sheet material through the forming assembly. The pulling assembly includes at least two grippers movable together through a transfer region in transverse opposition to one another and cooperative to grip therebetween the dunnage strip for advancing the dunnage strip through the transfer region. At least one of the grippers includes an aperture operative to gather and laterally capture therein the dunnage strip as the grippers move through the transfer region.
In an embodiment, an aperture in each gripper tapers in width going from an outer to an inner end of the gripper. The aperture of each gripper preferably is V-shape and may include a rounded bottom. The opposing grippers have contact regions operative to deform opposite sides of the strip of dunnage to capture the strip of dunnage between the opposing grippers.
In an embodiment, the grippers move through the transfer region in longitudinally offset yet paired relation for gripping and advancing the strip of dunnage. The opposing grippers may transversely overlap while advancing the strip of dunnage.
In another embodiment, the grippers are arranged in transversely opposed sets of grippers disposed on opposite transverse sides of the transfer region. The grippers of the opposed sets progressively move towards one another at an upstream end of the transfer region and progressively move away from one another at a downstream end of the transfer region. In an embodiment, the grippers of each set are circumferentially spaced around a common axis and are joined together for rotation about the common axis. The grippers of each set may extend perpendicularly, or at a different angle, relative to the respective common axis.
In yet another embodiment, the pulling assembly includes a set of transfer assemblies having connected thereto the respective sets of grippers. The transfer assemblies are operative to move the grippers of the respective set toward each other at the upstream end of the transfer region to transversely engage the strip of dunnage and away from each other at the downstream end of the transfer region to release the strip of dunnage. The grippers of each set may be movable along a non-circular path in opposite relation to one another and may be operative sequentially, as the grippers move along the non-circular path in opposite relation, to transversely engage the strip of dunnage therebetween on opposite sides thereof for advancing therewith the strip of dunnage. The opposing grippers downstream of the non-circular path preferably gradually release the strip of dunnage. The opposing grippers moving downstream of the non-circular path preferably release the strip of dunnage substantially simultaneously with or after opposing grippers moving along the non-circular path, upstream of the non-circular path, engage the strip of dunnage to advance the same.
An exemplary transfer assembly includes a flexible transfer element and a pair of wheels mounted on respective longitudinally spaced axles, the flexible transfer element having portions thereof trained over the pair of wheels, and wherein the grippers of said respective opposing sets of grippers are affixed to and extend from said respective flexible transfer elements such that at least one gripper from each of said respective opposing sets of grippers are in operative engagement with the strip of dunnage when moving along the non-circular path. The grippers of each set may extend perpendicularly, or at a different angle, relative to the respective flexible transfer element. Also, as is preferred, upon rotation of the pair of wheels, the at least one gripper from each of said respective opposing sets of grippers is longitudinally offset to provide clearance therebetween upon convergence thereof. The flexible transfer elements of the transfer assemblies may comprise articulating chains, flexible belts, or any other means of transferring rotary motion. Preferably, movement of the flexible transfer elements is synchronized.
A forming assembly according to the invention preferably includes a constriction member through which the sheet material is pulled to effect crumpling thereof and forming of the strip of dunnage. The constriction member may be a ring which is, for example, oval and has rounded edges at the upstream end thereof. The constriction member is preferably at an upstream end of the forming assembly. The constriction member constricts and guides the strip of dunnage from a downstream end of the forming assembly to an engagement region between the opposing grippers. The constriction member preferably defines an oval or otherwise round aperture through which the strip of dunnage is compressed circumferentially, the width of the aperture being smaller than the width of the sheet material.
In another embodiment, the grippers are arranged in transversely opposed first and second sets of grippers connected to respective first and second gripper carriages disposed on opposite transverse sides of the transfer region. The first gripper carriage is operative to move longitudinally the first set of grippers along a first non-circular path and the second gripper carriage is operative to move longitudinally the second set of grippers in synchronous relation to the first set of grippers along a second non-circular path. Portions of the first and second paths are juxtaposed to define therebetween the transfer region. At least one gripper of the first set of grippers and at least one gripper of the second set of grippers are operative to transversely engage the strip of dunnage on opposite sides thereof for advancing the strip of dunnage through the transfer region. The transfer region may include an engagement region whereat the first and second non-circular paths converge toward one another, an advancement region whereat the first and second non-circular paths are substantially parallel to one another, and a release region whereat the first and second non-circular paths diverge away from one another.
In an embodiment, the pulling assembly includes first and second transfer elements and first and second series of wheels. The first and second transfer elements are trained over the respective first and second series of wheels and include one or more grippers extending therefrom. The first and second series of wheels rotate in opposite directions and the first and second transfer elements are opposed to define the transfer region therebetween. The grippers of the respective first and second transfer elements are progressively brought into opposing relation to engage and transfer the strip of dunnage through the transfer region. As the first and second series of wheels rotate, the grippers of the respective first and second transfer elements converge toward one another at an upstream end of the dunnage transferring mechanism to engage opposite sides of the strip of dunnage, transfer the strip of dunnage through the transfer region, and then diverge away from one another at a downstream end of the dunnage transferring mechanism to release the strip of dunnage.
According to another aspect of the invention, there is provided a severing assembly for a dunnage conversion machine. The severing assembly severs the dunnage strip into a severed section of dunnage. The machine includes conversion assemblies for converting the sheet material into a continuous strip of dunnage and the severing assembly is positioned relative to the conversion assemblies to sever the continuous strip of dunnage into a severed section of a desired length. The severing assembly includes a movable blade and a reciprocating actuator connected to the movable blade by a motion transmitting assembly that moves the movable blade from a ready-to-sever position to a severed position and back to a ready-to-sever position upon a single stroke of the reciprocating actuator in either direction. The severing assembly may include a stationary blade which coacts with the movable blade as the movable blade moves to the severed position. Preferably, the movable blade coacts with the stationary blade in a scissor-like fashion.
According to another aspect of the invention, there is provided a dunnage conversion machine for converting sheet material, such as paper having at least one ply, into a severed section of dunnage. The dunnage conversion machine includes conversion assemblies for converting the sheet material into a continuous strip of dunnage and a severing assembly positioned relative to the conversion assemblies to sever the continuous strip of dunnage into a severed section of a desired length. The severing assembly includes a movable blade and a reciprocating actuator connected to the movable blade by a motion transmitting assembly that moves the movable blade from a ready-to-sever position to a severed position and back to a ready-to-sever position upon a single stroke of the reciprocating actuator in either direction.
In an embodiment, the dunnage conversion machine further includes an end plate having an upstream side and a downstream side. The conversion assemblies are positioned upstream of the end plate and the end plate has a dunnage outlet opening through which the strip of dunnage emerges. The severing assembly is operative to sever the continuous strip of dunnage after a length of the strip of dunnage has passed through the outlet opening. As is preferred, the movable blade is mounted to the downstream side of the end plate and coupled to the motion-transmitting assembly, the movable blade being movable in a plane parallel to the plane defined by the outlet opening and across the outlet opening as it travels between the ready-to-sever position and the severed position.
In another embodiment, the motion-transmitting assembly includes at least one linkage member pivotally coupled to the movable blade. Preferably, guide plates are mounted on the end plate adjacent the outlet opening and the movable blade is slidably retained within the guide plates whereby, as the reciprocating actuator is moved either in a single forward stroke or a single return stroke, the position of the linkage member will be varied to pivot the movable blade from the ready-to-sever position to the severed position and back to the ready-to-sever position. In another embodiment, one end of the movable blade is pivotally mounted to the end plate at a pivot point, whereby as the reciprocating actuator is moved either in a single forward stroke or a single return stroke, the position of the linkage member will be varied to pivot the movable blade from the ready-to-sever position to the severed position and back to the ready-to-sever position.
In still another embodiment, the severing assembly includes a flared guide member mounted to the upstream side of the end plate for guiding the continuous strip of dunnage into the dunnage outlet opening.
In an embodiment, the conversion assemblies include a forming assembly which shapes the sheet material into the continuous strip of dunnage, a stock supply assembly which supplies the sheet material to the forming assembly, and a pulling assembly which pulls the sheet material from the stock supply assembly and through the forming assembly to form the strip of dunnage.
According to yet another aspect of the invention, there is provided a method of severing a continuous strip of dunnage into a severed section of a desired length, including the steps of using conversion assemblies for converting sheet material, such as paper having at least one ply, into a continuous strip of dunnage, and using a severing assembly positioned relative to the conversion assemblies to sever the continuous strip of dunnage into a severed section of a desired length, wherein the severing assembly includes a movable blade and a reciprocating actuator connected to the movable blade by a motion transmitting assembly. Moving the reciprocating actuator a single stroke causes the motion transmitting assembly to move the movable blade from a ready-to-sever position to a severed position and back to the ready-to-sever position.
In an embodiment, the step of moving the reciprocating actuator includes extending the reciprocating actuator in a forward stroke whereby the movable blade is moved from the ready-to-sever position, to the severed position and back to the ready-to-sever position. In another embodiment, the step of moving the reciprocating actuator includes retracting the reciprocating actuator in a return stroke whereby the movable blade is moved from the ready-to-sever position, to the severed position and back to the ready-to-sever position.
According to another aspect of the invention, there is provided a void fill dunnage product comprising a three dimensional crumpled strip of dunnage round in cross-section and including at least one ply of sheet material having, in cross-section, a crumpled multi-lobed undulating body, with the lobes thereof extending longitudinally and being dispersed in an irregular pattern. The void fill product preferably has the highest possible volume and stability, while using the least possible amount of raw material. As was noted above, this is achieved by the present invention by producing the noted generally cylindrical product whose stability can yet be further increased by making the same generally curved and/or by permanently deforming the cross-sections of selected spaced portions of the product.
In an embodiment, there is at least one transverse crimp on opposite transverse sides of the strip of dunnage. Preferably, the crimps are longitudinally offset from one another.
According to yet another aspect of the invention, there is provided a method of producing a dunnage product, the method comprising the steps of supplying a sheet material having at least one ply and causing inward folding of the lateral edges of the at least one ply of sheet material whereby a three-dimensional crumpled strip of dunnage of round cross-sectional shape is formed. The at least one ply of sheet material forms, in cross-section, a crumpled multi-lobed undulating body, the lobes thereof extending longitudinally and being dispersed in an irregular pattern.
In an embodiment, the strip of dunnage is regularly transversely crimped and/or kinked on opposite sides thereof. Preferably, the crimp on one side is longitudinally offset from the crimp on the opposite side thereof. In an embodiment, the method further includes the step of using a pulling assembly for pulling the strip of dunnage through a constriction member to both narrow the strip of dunnage via three dimensional crumpling thereof and to guide the strip of dunnage to the pulling assembly. The constriction member ensures a substantially jam-free flow of the strip of dunnage through the pulling assembly.
The foregoing and other features of the invention are hereinafter more fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail illustrative embodiments of the invention, such being indicative, however, of but one or a few of the various ways in which the principles of the invention may be employed.